An example of a technology regarding the power supply of a storage system is the technology disclosed in Patent Citation 1. Patent Citation 1, for example, discloses the following.
As shown in FIG. 1, the storage system 500 has one or more chassis 501 and redundant power supply units 503A and 503B. The power supply unit 503A (503B) includes a 56-volt power supply 504A (504B) (the AC/DC converter which converts AC voltage from the AC power supply into 56-volt DC voltage). The chassis 501, as shown in FIG. 2, includes multiple canisters 502. Each canister 502 includes an HDD (Hard Disk Drive) 509, a 12-volt power supply 507 (DC/DC converter which lowers DC voltage from 56-volt to 12-volt), a 5-volt power supply 508 (DC/DC converter which lowers DC voltage from 56-volt to 5-volt) and a backflow prevention elemental device 519 (for example, a diode).
In the canister 502, one power feeding path (hereinafter referred to as “first path”) includes a backflow prevention elemental device 519, and the other power feeding path (hereinafter referred to as “second path”) includes two backflow prevention elemental devices 519. Usually, power is supplied from one 56-volt power supply 504A through the first path (main power feeding path) to the power supply 507 and 508 in each canister 502, and in case of failure, power is supplied from the other 56-volt power supply 504B through the second path to the power supply 507 and 508 in each canister 502. That is, a power supply boundary 510 is supposed to be formed in each canister 502. “Power supply boundary” indicates the configuration where, in the system which includes a power feeding system in each load group configured of one or more loads (according to FIG. 2, a load group is an HDD 509), includes boundaries among the power feeding systems so that, even if the power feeding path in one power feeding system shorts out and consequently power is not supplied to the load group corresponding to the power feeding system, power feeding will be continued through the power feeding path of another power feeding system to the other load groups. In other words, each power supply boundary is each of the load groups corresponding to the power feeding systems.